<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>@-rules</title>
    <link rel="stylesheet" href="./index.css">
</head>
<body>
    <div class="wrap-box">
        <h1 class="title1">我是h1</h1>
        <h1 class="title2">我是h2</h1>
        <h1 class="title3">
            <div class="child1">
                <p class="child2">
                    <i class="child3">child</i>
                </p>
            </div>
        </h1>
        <div class="is-na">
            <h1>na</h1>
        </div>
        <div class="is-pc">
            <h1>pc</h1>
        </div>
        <div class="ctx-box">
            <div class="tx">hello@ if</div>
        </div>
    </div>
</body>
</html>